Light from the hottest young stars usually cannot leave its galaxy: hydrogen absorbs it, like a thick curtain blocking a sunbeam. But sometimes the curtain parts, and ultraviolet photons burst into intergalactic space. It is precisely this kind of "escaped" radiation that has now been caught for the first time from three massive spiral galaxies, so far away that their light took nearly eight billion years to reach Earth.
All three galaxies face us almost "face-on"—their disks are turned toward the observer, not edge-on. Perhaps this is why the light managed to escape: in this orientation, there is less dense gas in the line of sight. Two of the three galaxies have active nuclei, supermassive black holes devouring matter, and their contribution still needs to be disentangled. But one galaxy most likely shines thanks to its stars, and its example shows that even large spiral systems have "windows" for escaping light.
This discovery suggests that to understand how young stars illuminated the early universe, we must consider not only the galaxy's composition but also how it is oriented to us. Light may escape not uniformly in all directions but in narrow beams, like water finding cracks in a dam.
The light from these galaxies began its journey when dinosaurs had not yet appeared on Earth — about 8 billion years ago.
In Robert Wilson's novel "Spin," stars go out because their light cannot pass through a barrier — here, the opposite happens: light finds a loophole in the gas veil.